Although some of the presently known automatic car couplers of the type used for rapid transit equipment for automatically effecting concurrent coupling of the cars, the air conduits, and the electrical circuits when the cars are brought together, are provided with visual indicators visible from both sides of the train without the necessity of passing from one side of the train to the other for ascertaining that locking of both heads has positively been effected, such known indicator means may possibly possess certain objectionable characteristics. The above-mentioned type of indicator may comprise an axially flexible, closely wound spring attached at one end to an axially movable locking member of the coupler and slidably disposed in a fixed guide tube such that when the locking member is in a locked condition, the spring member is fully retracted within the guide tube, but if the locking member is in an unlocked condition, a certain amount of the free end of the spring member protrudes or projects beyond the open end of the guide tube, thus indicating an unlocked condition. If the guide tube, during service, inadvertently became pinched or crimped, the spring could possibly become jammed in the tube and thereby cause the locking member to hang up. Moreover, the loose end of the coil spring could also possibly catch on the open end of the guide tube to prevent free movement thereof and of the locking member.